Censuses provide good opportunities for studying migration-related phenomena, since most states include questions on citizenship status, country of origin, and previous places of residence. Whereas aggregated censuses data provide summary information on areas and/or groups, census microdata is capable to report individual responses. Generally, challenges of accessing data and international differences complicate working comparatively with census data; however, individual organisations help with harmonizing and pooling it into a single database. Furthermore, some censuses also provide for detailed information to study living conditions of specific migrant groups, such as labour market integration, access to basic services, and education opportunities.